Acoustic device and method of using the same
The disclosed acoustic device and method of using the same allow perception of a bright, clear sound. In an acoustic device (1) for transmitting sound to a user through vibration conduction by contacting a vibrating body (10a) to a human auricle, when a measurement system (10), provided with an ear model (50) including an artificial auricle (51) and an artificial external ear canal (53) and with a microphone (62) that measures air-conducted sound in the artificial external ear canal (53), measures the air-conducted sound upon the acoustic device (1) outputting a fundamental frequency at a predetermined frequency in an audible frequency band while placed in contact with the ear model (50), three or more harmonics at or above the sixth harmonic and having a volume exceeding a volume 45 dB below the volume of the fundamental frequency are measured.
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This application claims priority to and the benefit of Japanese Patent Application No. 2013-112612 filed May 29, 2013, the entire contents of which are incorporated herein by reference.
TECHNICAL FIELDThis disclosure relates to an acoustic device, such as a hearing aid, and to a method of using the same.
BACKGROUNDOne type of acoustic device uses a bone conduction technique that causes a user to hear sound by contacting a vibrating body to the user's auricle, such as the tragus or the like of the ear (for example, see JP 2005-348193 A (PTL 1)). An acoustic device using a bone conduction technique transmits vibration directly to the auditory nerve and thus places little strain on the eardrum. Such an acoustic device is therefore better than an earphone, headphone, or other acoustic device that does not use a bone conduction technique.
CITATION LIST Patent LiteraturePTL 1: JP 2005-348193 A
SUMMARY Technical ProblemAn acoustic device using a bone conduction technique, however, suffers from the problem of sound being occluded, making it difficult to output high-frequency sound. The reason is that few harmonics are included in the sound output by such an acoustic device. A harmonic is sound at a frequency that is an integer multiple (two or greater) of the frequency of the output sound (fundamental frequency). In general, when few harmonics are included in the sound output by an acoustic device, the resulting sound is not well-defined and seems obscure and occluded. On the other hand, when many harmonics are included in the sound output by an acoustic device, the result is a bright, clear, sharply-defined sound. When the sound pressure of harmonics at even higher frequencies is high, the result is a sharp, hard sound, whereas when the sound pressure of low-frequency harmonics is high, the result is a soft yet strong sound.
As an acoustic device that transmits sound to a user by vibration conduction, such as bone conduction, it would therefore be helpful to provide an acoustic device, and a method of using the same, that generates harmonics and allows the user to perceive a bright, clear sound.
Solution to ProblemIn order to solve the above problem, the disclosed acoustic device is for transmitting sound to a user through vibration conduction by contacting a vibrating body to a human auricle, such that when a measurement system, provided with an ear model including an artificial auricle and an artificial external ear canal and with a microphone that measures air-conducted sound in the artificial external ear canal, measures the air-conducted sound upon the acoustic device outputting a fundamental frequency at a predetermined frequency in an audible frequency band while placed in contact with the ear model, three or more harmonics at or above a sixth harmonic and having a volume exceeding a volume 45 dB below a volume of the fundamental frequency are measured.
Advantageous EffectThe acoustic device and method of using the same of this disclosure generate harmonics and allow perception of a bright, clear sound.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. In the accompanying drawings:
The following describes embodiments with reference to the drawings.
Embodiment 1When the disclosed acoustic device is measured with the measurement system described in detail below, predetermined harmonics are measured. First, the disclosed measurement system is described.
Structure and Operations of Measurement System
The ear model 50 is modeled after a human ear and includes an artificial auricle 51 and artificial external ear canal unit 52 joined to the artificial auricle 51. The artificial external ear canal unit 52 is large enough to cover the artificial auricle 51 and has an artificial external ear canal 53 formed in the central region thereof. The ear model 50 is supported by the base 30 via a support member 54 at the periphery of the artificial external ear canal unit 52.
The ear model 50 is made from similar material to the material of an average artificial auricle used in, for example, a manikin such as a Head And Torso Simulator (HATS), Knowles Electronic Manikin for Acoustic Research (KEMAR), or the like, such as material conforming to IEC 60318-7. This material may, for example, be formed with a material such as rubber having a hardness of 35 to 55. The hardness of rubber may, for example, be measured in conformity with International Rubber Hardness Degrees (IRHD/M) conforming to JIS K 6253, ISO 48, or the like. As a hardness measurement system, a fully automatic IRHD/M micro-size international rubber hardness gauge GS680 by Teclock Corporation may suitably be used. Note that taking the variation in ear hardness due to age into account, as a rule of thumb, approximately two or three types of the ear model 50 with a different hardness are preferably prepared and used interchangeably.
The thickness of the artificial external ear canal unit 52, i.e. the length of the artificial external ear canal 53, corresponds to the length up to the human eardrum (cochlea) and for example is suitably set in a range of 20 mm to 40 mm. In this embodiment, the length of the artificial external ear canal 53 is approximately 30 mm.
In the ear model 50, a vibration gauge 55 is disposed on the end face of the artificial external ear canal unit 52 on the opposite side from the artificial auricle 51, at a position in the peripheral portion of the opening of the artificial external ear canal 53. The vibration gauge 55 detects the amount of vibration transmitted through the artificial external ear canal unit 52 when the vibrating body of the acoustic device 1 is placed against the ear model 50. In other words, the vibration gauge 55 detects the amount of vibration corresponding to the human body vibration sound component that is heard without passing through the eardrum when the vibrating body of the acoustic device 1 is pressed against a human ear and vibration of the vibrating body of the acoustic device 1 directly vibrates the inner ear. Human body vibration sound as referred to here is sound that is transmitted to the user's auditory nerve through a portion of the user's body (such as the cartilage of the outer ear) that is contacting a vibrating object. The vibration gauge 55 is, for example, configured using a vibration detection element 56 that has flat output characteristics in the measurement frequency range of the acoustic device 1 (for example, from 0.1 kHz to 30 kHz), is lightweight, and can accurately measure even slight vibrations. An example of this vibration detection element 56 is a piezoelectric acceleration pickup or other such vibration pickup, such as the vibration pickup PV-08A produced by Rion Corporation or the like.
While
Furthermore, a sound pressure measurement unit 60 is disposed in the ear model 50. The sound pressure measurement unit 60 measures the sound pressure of sound propagating through the artificial external ear canal 53. In other words, the sound pressure measurement unit 60 measures the sound pressure produced when the vibrating body of the acoustic device 1 is pressed against a human ear. This sound pressure includes sound pressure corresponding to air-conducted sound that is heard directly through the eardrum by air vibrating due to vibration of the vibrating body of the acoustic device 1 and sound pressure corresponding to air-conducted sound representing sound, heard through the eardrum, that is produced in the ear itself by the inside of the external ear canal vibrating due to vibration of the vibrating body of the acoustic device 1. Air-conducted sound as referred to here is sound transmitted to the user's auditory nerve by air vibrations, caused by a vibrating object, that are transmitted through the external ear canal to the eardrum and cause the eardrum to vibrate.
As illustrated by the cross-sectional view in
Next, the holder 70 is described. The holder 70 is provided with a support 71 that supports both sides of the acoustic device 1. The support 71 is attached to one end of an arm 72 so as to be rotatable about an axis y1, which is parallel to the y-axis, in a direction to press the acoustic device 1 against the ear model 50. The other end of the arm 72 is joined to a movement adjuster 73 provided on the base 30. The movement adjuster 73 can adjust movement of the arm 72 in a vertical direction x1 of the acoustic device 1 supported by the support 71, the direction x1 being parallel to the x-axis that is orthogonal to the y-axis, and in a direction z1 that presses the acoustic device 1 against the ear model 50, the direction z1 being parallel to the z-axis that is orthogonal to the y-axis and the x-axis.
In this way, in the acoustic device 1 supported by the support 71, the pressing force, against the ear model 50, of the vibrating body is adjusted by rotating the support 71 about the axis y1 or by moving the arm 72 in the z1 direction. In this embodiment, the pressing force is adjusted in a range of 0 N to 10 N. Of course, the support 71 may also be configured to rotate freely about other axes in addition to the y1 axis.
The reason for the range from 0 N to 10 N is to allow measurement over a range that is sufficiently wider than the pressing force that is envisioned when a human presses the acoustic device against an ear, for example to converse. The case of 0 N may, for example, include not only the case of contacting without pressing against the ear model 50, but also the case of holding the acoustic device 1 at a distance from the ear model 50 in increments of 1 cm and measuring at each distance. This approach also allows measurement with the microphone 62 of the degree of damping of air-conducted sound due to distance, thus making the measurement system more convenient.
By adjusting the arm 72 in the x1 direction, the contact position of the acoustic device 1 with respect to the ear model 50 can be adjusted so that, for example, the vibrating body covers nearly the entire ear model 50, or so that the vibrating body covers a portion of the ear model 50, as illustrated in
Next, the structure of the measurement unit 200 in
Output of the vibration detection element 56 and the microphone 62 is provided to the sensitivity adjuster 300. The sensitivity adjuster 300 includes a variable gain amplifier circuit 301 that adjusts the amplitude of the output of the vibration detection element 56 and a variable gain amplifier circuit 302 that adjusts the amplitude of the output of the microphone 62. The amplitudes of analog input signals, corresponding to the respective circuits, are independently adjusted to required amplitudes either manually or automatically. Error in the sensitivity of the vibration detection element 56 and the sensitivity of the microphone 62 is thus corrected. Note that the variable gain amplifier circuits 301 and 302 are configured to allow adjustment of the amplitude of the input signals over a range of, for example, ±20 dB.
Output of the sensitivity adjuster 300 is input into the signal processor 400. The signal processor 400 includes an A/D converter 410, frequency characteristic adjuster 420, phase adjuster 430, output combiner 440, frequency analyzer 450, memory 460, and signal processing controller 470. The A/D converter 410 includes an A/D conversion circuit (A/D) 411 that converts the output of the variable gain amplifier circuit 301 into a digital signal and an A/D conversion circuit (A/D) 412 that converts the output of the variable gain amplifier circuit 302 into a digital signal. The analog input signal corresponding to each circuit is thus converted into a digital signal. The A/D conversion circuits 411 and 412 are, for example, 16 bits or more and can support 96 dB or more by dynamic range conversion. The A/D conversion circuits 411 and 412 may also be configured so that the dynamic range is changeable.
Output of the A/D converter 410 is provided to the frequency characteristic adjuster 420. The frequency characteristic adjuster 420 includes an equalizer (EQ) 421 that adjusts the frequency characteristic of the detection signal from the vibration detection element 56, i.e. the output of the A/D conversion circuit 411, and an equalizer (EQ) 422 that adjusts the frequency characteristic of the detection signal from the microphone 62, i.e. the output of the A/D conversion circuit 412. The frequency characteristics of the respective input signals are independently adjusted to frequency characteristics near the auditory sensation of the human body either manually or automatically. The equalizers 421 and 422 may, for example, be configured with a graphical equalizer having a plurality of bands, a low pass filter, a high pass filter, or the like. The order in which the equalizers (EQ) and the A/D conversion circuits are disposed may be reversed.
Output of the frequency characteristic adjuster 420 is provided to the phase adjuster 430. The phase adjuster 430 includes a variable delay circuit 431 that adjusts the phase of the detection signal from the vibration detection element 56, i.e. the output of the equalizer 421. In other words, since the speed of sound transmitted through the material of the ear model 50 is not exactly the same as the speed of sound transmitted through human muscle or bone, it is assumed that the phase relationship between the output of the vibration detection element 56 and the output of the microphone 62 will be shifted from that of a human ear, the shift being greater at high frequencies.
If the phase relationship between the output of the vibration detection element 56 and the output of the microphone 62 thus shifts greatly, then upon combining the two outputs with the below-described output combiner 440, amplitude peaks and dips may appear at different values than in actuality, and the combined output may be amplified or diminished. For example, if the transmission speed of sound detected by the microphone 62 is 0.2 ms slower than the transmission speed of vibration detected by the vibration detection element 56, then the combined output of both as sinusoidal vibration at 2 kHz is as illustrated in
Therefore, in this embodiment, in accordance with the measurement frequency range of the acoustic device 1 targeted for measurement, the phase of the detection signal from the vibration detection element 56, which is the output of the equalizer 421, is adjusted over a predetermined range by the variable delay circuit 431. For example, in the case of the measurement frequency range of the acoustic device 1 being from 100 Hz to 10 kHz, the phase of the detection signal from the vibration detection element 56 is adjusted by the variable delay circuit 431 over a range of approximately ±10 ms (corresponding to ±100 Hz) at least in increments smaller than 0.1 ms (corresponding to 10 kHz). In the case of a human ear as well, phase misalignment occurs between human body vibration sound and air-conducted sound. Therefore, phase adjustment by the variable delay circuit 431 does not refer to matching the phase of the detection signals from the vibration detection element 56 and the microphone 62, but rather to matching the phase of these detection signals to the actual auditory sensation by the ear.
Output of the phase adjuster 430 is provided to the output combiner 440. The output combiner 440 combines the detection signal from the vibration detection element 56, after phase adjustment by the variable delay circuit 431, with the detection signal, from the microphone 62, that has passed through the phase adjuster 430. This enables approximation of the human body in obtaining sensory sound pressure that combines the amount of vibration and the sound pressure, i.e. the human body vibration sound and the air-conducted sound, transmitted by vibration of the acoustic device 1 targeted for measurement.
The combined output of the output combiner 440 is input into the frequency analyzer 450. The frequency analyzer 450 includes a Fast Fourier Transform (FFT) 451 that performs frequency analysis on the combined output of the output combiner 440. In this way, power spectrum data corresponding to the sensory sound pressure (air+vib), in which the human body vibration sound (vib) and the air-conducted sound (air) are combined, are obtained from the FFT 451.
Furthermore, in this embodiment, the frequency analyzer 450 is provided with FFTs 452 and 453 that perform frequency analysis on the signals before combination by the output combiner 440, i.e. on the detection signal, from the vibration detection element 56, that has passed through the phase adjuster 430 and the detection signal from the microphone 62. In this way, power spectrum data corresponding to the human body vibration sound (vib) are obtained from the FFT 452, and power spectrum data corresponding to the air-conducted sound (air) are obtained from the FFT 453.
In the FFTs 451 to 453, analysis points are set for the frequency component (power spectrum) in correspondence with the measurement frequency range of the acoustic device 1. For example, when the measurement frequency range of the acoustic device 1 is 100 Hz to 10 kHz, analysis points are set so as to analyze the frequency component at each point when dividing the interval in a logarithmic graph of the measurement frequency range into 100 to 200 equal portions.
The output of the FFTs 451 to 453 is stored in the memory 460. The memory 460 has the capacity of at least a double buffer that can store a plurality of analysis data sets (power spectrum data) for each of the FFTs 451 to 453. The memory 460 is configured to always allow transmission of the latest data upon a data transmission request from the below-described PC 500.
The signal processing controller 470 is connected to the PC 500 via a connection cable 510 for an interface such as USB, RS-232C, SCSI, PC card, or the like. Based on commands from the PC 500, the signal processing controller 470 controls operations of each portion of the signal processor 400. The signal processor 400 may be configured as software executed on any suitable processor, such as a central processing unit (CPU), or may be configured with a digital signal processor (DSP).
The PC 500 includes an application to evaluate the acoustic device 1 with the measurement system 10. The evaluation application is copied from a CD-ROM or downloaded over a network or the like. The PC 500 for example displays an application screen on a display 520 based on the evaluation application. Based on information input via the application screen, the PC 500 transmits a command to the signal processor 400. The PC 500 also receives a command acknowledgment and data from the signal processor 400, and based on the received data, executes predetermined processing and displays the measurement results on the application screen. As necessary, the PC 500 also outputs the measurement results to the printer 600 to print the measurement results.
In
The “Calibration” icon 522 corrects error in the sensitivity of the vibration detection element 56 and the microphone 62. In this correction mode, a reference device is set in the holder 70 and brought into contact with the ear model 50 at a reference position. When causing the reference device to vibrate in a predetermined vibration mode (for example, a pure tone or a multi-sine), the sensitivity of the vibration detection element 56 and of the microphone 62 is adjusted by the variable gain amplifier circuits 301 and 302 so that the power spectrum data of the detection signal from the vibration detection element 56 and the power spectrum data of the detection signal from the microphone 62 are within their respective normal error ranges.
The “Measure Start” icon 523 transmits a measurement start command to the signal processor 400 and continues to receive data until the end of measurement. The “Measure Stop” icon 524 transmits a measurement stop command to the signal processor 400 and ends data reception. Based on the received data, measurement results corresponding to the measurement mode selected with the measurement type icon 529 are displayed in the measurement result display area 525.
The measurement result display selection area 527 displays types of power spectra that can be displayed in the measurement result display area 525 and a selection box for each type, along with a display area and a selection box for each of the current value of the power spectrum (Now), the maximum value during measurement (Max), and the average value during measurement (Average). The power spectrum or high-frequency distortion rate are also displayed in the corresponding areas for the information selected with the selection boxes. The file icon 528 is, for example, for printing the application screen being displayed or for outputting the measurement results in a format such as CSV or EXCEL. The measurement type icon 529 switches between measurement modes, such as power spectrum measurement mode, high-frequency distortion rate measurement mode, and the like. The high-frequency distortion rate displayed in the measurement result display selection area 527 can be calculated in high-frequency distortion rate mode by the PC 500 based on measurement data from the signal processor 400. The help icon 530 displays help on how to use the measurement system 10.
The measurement system 10 of this embodiment evaluates the acoustic device 1 targeted for measurement by analyzing frequency components in the combined output of the vibration detection element 56 and the microphone 62 while using a piezoelectric element, for example, to cause the vibrating body of the acoustic device 1 to vibrate. The piezoelectric element with which the vibrating body is configured may have a predetermined measurement frequency range of, for example, 100 Hz to 10 kHz as mentioned above and may be driven with a multi-drive signal wave that combines drive signals for every 100 Hz.
With reference to the flowchart in
First, upon the “Measure Start” icon 523 on the application screen 521 in
Simultaneously, the signal processor 400 performs frequency analysis with the FFT 452 on the detection signal from the vibration detection element 56, the phase of which was adjusted by the variable delay circuit 431 of the phase adjuster 430, and stores the power spectrum data for 100 points, i.e. the “vib” data, in the memory 460. Similarly, the signal processor 400 performs frequency analysis with the FFT 453 on the detection signal, from the microphone 62, that passed through the phase adjuster 430 and stores the power spectrum data for 100 points, i.e. the “air” data, in the memory 460.
The signal processor 400 repeats the FFT processing by the FFTs 451 to 453 at predetermined timings and stores the results in the memory 460. The memory 460 thus stores the data from the FFTs 451 to 453 by consecutively updating the data so as always to retain the latest data.
Subsequently, the PC 500 activates a timer at a predetermined timing and transmits a command for a data transmission request to the signal processor 400. Upon receiving the data transmission request from the PC 500, the signal processor 400 consecutively transmits 100 points each of the latest “vib” data, “air” data, and “air+vib” data stored in the memory 460 to the PC 500.
Until transmitting a measurement stop command to the signal processor 400, the PC 500 continues to transmit a command for the data transmission request to the signal processor 400 at each set time of the timer, thereby acquiring the latest “vib” data, “air” data, and “air+vib” data. Upon each acquisition of data from the signal processor 400, the PC 500 displays the measurement results on the application screen 521 in
Subsequently, upon the “Measure Stop” icon 524 on the application screen 521 in
The measurement results illustrated in
As is clear from
Furthermore, in this embodiment, the microphone 62 measures sound pressure through the ear model 50. Accordingly, the power spectrum corresponding to the air-conducted component measured based on output of the microphone 62 is a combination of the sound pressure corresponding to the air-conducted component that is heard directly through the eardrum by air vibrating due to vibration of the acoustic device 1 and sound pressure corresponding to the air-conducted component representing sound, heard through the eardrum, that is produced in the ear itself by the inside of the external ear canal vibrating due to vibration of the acoustic device 1. In other words, the power spectrum corresponding to the air-conducted component measured with this embodiment is weighted for the characteristics of sound pressure transmission in a human ear.
Moreover, in the measurement system 10 of this embodiment, after the phases of the output corresponding to the human body vibration sound component from the vibration detection element 56 and the output corresponding to the air-conducted component from the microphone 62 are adjusted by the phase adjuster 430, the two outputs are combined by the output combiner 440 and subjected to frequency analysis by the frequency analyzer 450. Accordingly, the sensory sound pressure that combines the amount of vibration and the sound pressure conducted to the human body due to vibration of the acoustic device 1 targeted for measurement can be measured by approximating the human body. This approach enables evaluation of the acoustic device 1 to a high degree of accuracy and increases the reliability of the measurement system 10.
In this embodiment, the output corresponding to the human body vibration sound component from the vibration detection element 56 and the output corresponding to the air-conducted component from the microphone 62 are independently subjected to frequency analysis by the frequency analyzer 450, thereby allowing more detailed evaluation of the acoustic device 1. Furthermore, the sensitivity of the vibration detection element 56 and of the microphone 62 is adjusted by the sensitivity adjuster 300, thereby allowing measurement of sensory sound pressure by age or the like. Hence, the acoustic device 1 can be evaluated in accordance with the function of an individual's ear. Also, since the frequency characteristics of the output corresponding to the human body vibration sound component from the vibration detection element 56 and of the output corresponding to the air-conducted component from the microphone 62 can be adjusted independently with the frequency characteristic adjuster 420, the acoustic device 1 can be evaluated to a high degree of accuracy in accordance with the function of an individual's ear.
Furthermore, the acoustic device 1 targeted for measurement can adjust the pressing force on the ear model 50 and can also adjust the contact position, thus allowing a variety of forms of evaluating the acoustic device 1.
Structure of Acoustic Device
Next, the acoustic device of this disclosure is described.
The vibrating body 10a includes a piezoelectric element 101a that flexes and a panel 102a that vibrates by being bent directly by the piezoelectric element 101a.
The piezoelectric element 101a is formed by elements that, upon application of an electric signal (voltage), either expand and contract or bend (flex) in accordance with the electromechanical coupling coefficient of their constituent material. Ceramic or crystal elements, for example, may be used. The piezoelectric element 101a may be a unimorph, bimorph, or laminated piezoelectric element. Examples of a laminated piezoelectric element include a laminated unimorph element with layers of unimorph (for example, 16 or 24 layers) and a laminated bimorph element with layers of bimorph (for example, 16 or 24 layers). Such a laminated piezoelectric element may be configured with a laminated structure formed by a plurality of dielectric layers composed of, for example, lead zirconate titanate (PZT) and electrode layers disposed between the dielectric layers. Unimorph expands and contracts upon the application of an electric signal (voltage), and bimorph bends upon the application of an electric signal (voltage). The surface of the piezoelectric element 101a that contacts the panel 102a (principal surface) preferably has a width of 4.0 mm and a length of 17.5 mm. The principal surface of the piezoelectric element 101a is described below as having a width of 4.0 mm and a length of 17.5 mm.
The panel 102a is, for example, made from glass or a synthetic resin such as acrylic or the like. An exemplary shape of the panel 102a is a plate, and the shape of the panel 102a is described below as being a plate.
The microphone 20a collects sound from a sound source, namely sound reaching the user's ear.
The controller 30a executes various control pertaining to the hearing aid 1. The controller 30a applies a predetermined electric signal (a voltage corresponding to a sound signal) to the piezoelectric element 101a. In greater detail, in the controller 30a, an A/D converter 31 converts a sound signal collected by the microphone 20a into a digital signal. Based on information on volume, sound quality, and the like from the volume and sound quality adjustment interface 40a and on information stored in the memory 50a, a signal processor 32 outputs a digital signal that drives the vibrating body 10a. A D/A converter 33a converts the digital signal to an analog electric signal, which is then amplified by a piezoelectric amplifier 34. The resulting electric signal is applied to the piezoelectric element 101a. The voltage that the controller 30a applies to the piezoelectric element 101a may, for example, be ±15 V. This is higher than ±5 V, i.e. the applied voltage of a so-called panel speaker for conduction of sound by air-conducted sound rather than human body vibration sound. In this way, sufficient vibration is generated in the panel 102a, so that a human body vibration sound can be generated via a part of the user's body. Note that the magnitude of the applied voltage used may be appropriately adjusted in accordance with the fixation strength of the panel 102a or the performance of the piezoelectric element 101a. Upon the controller 30a applying the electric signal to the piezoelectric element 101a, the piezoelectric element 101a expands and contracts or bends in the longitudinal direction.
At this point, the panel 102a to which the piezoelectric element 101a is attached vibrates by deforming in conjunction with the expansion and contraction or bending of the piezoelectric element 101a. The panel 102a flexes due to expansion and contraction or to bending of the piezoelectric element 101a. The panel 102a is bent directly by the piezoelectric element 101a. Stating that “the panel 102a is bent directly by the piezoelectric element 101a” differs from the phenomenon utilized in known panel speakers, whereby the panel 102a deforms upon vibration of a particular region of the panel 102a due to the inertial force of a piezoelectric actuator constituted by disposing the piezoelectric element 101a in the casing. Stating that “the panel 102a is bent directly by the piezoelectric element 101a” refers instead to how expansion and contraction or bending (flexure) of the piezoelectric element 101a directly bends the panel 102a via the joining member.
Since the panel 102a vibrates as described above, the panel 102a generates air-conducted sound, and when the user contacts the panel 102a to the tragus, the panel 102a generates human body vibration sound via the tragus. The panel 102a preferably vibrates with locations near the edges of the panel 102a as nodes and the central region as an antinode, and a location at the central region of the panel 102a preferably contacts the tragus or antitragus. As a result, vibration of the panel 102a can be efficiently transmitted to the tragus or the antitragus.
The attaching portion 12a for the pressing member is a member for attaching the pressing member 11a to the vibrating body 10a. The pressing member 11a and the attaching portion 12a are shaped to fit each other. The pressing member 11a preferably includes a concave cutout portion 111a, and the attaching portion 12a preferably has a convex shape that fits into the cutout portion 111a. The pressing member 11a can be detached from the vibrating body 10a by sliding in the width direction. The vibrating body 10a preferably has a thickness (D) of 4 mm or less and a width (W) of 15 mm or less. If the size is within this range, the vibrating body 10a can fit within the external ear canal of the user's ear regardless of gender or age (except for toddlers and below). The pressing member 11a also preferably comes in three sizes (small, medium, and large), with one of the pressing members 11a, 11b, and 11c being selected in accordance with the size of the user's ear and attached to the attaching portion 12a for the pressing member.
A holder 60a includes a support 61a, an ear hook 62a, and a body 63a. The holder 60a holds the vibrating body 10a at the position at which the vibrating body 10a contacts the user's ear (the inner wall of the external ear canal by the tragus). One end of the support 61a is connected to the vibrating body 10a. The support 61a has a hollow structure, and a lead wire is fed to the vibrating body 10a through this hollow structure. The support 61a is rigid enough so that the angle of the vibrating body 10a does not change. The other end of the support 61a is connected to one end of the ear hook 62a.
The ear hook 62a contacts the outside of the user's auricle to mount the hearing aid 1 in the user's ear. The ear hook 62a is preferably shaped as a hook conforming to the user's auricle so as to mount the hearing aid 1 stably in the user's ear. The other end of the ear hook 62a is connected to the body 63a. The body 63a stores the microphone 20a, controller 30a, volume and sound quality adjustment interface 40a, and memory 50a therein.
The piezoelectric element 101a is joined to the panel 102a by a joining member. The joining member is disposed between the principal surface of the piezoelectric element 101a and the principal surface of the panel 102a. The joining member is preferably a non-heat hardening adhesive material or double-sided tape.
Apart from the surface joined to the panel 102a, the piezoelectric element 101a is covered by a mold 103a. The pressing member 11a and the attaching portion 12a for the pressing member are provided at the top of the mold 103a.
The surface of the panel 102a that contacts the ear (principal surface) preferably has an area between 0.8 and 10 times the area of the principal surface of the piezoelectric element 101a. If the principal surface of the panel 102a has an area between 0.8 and 10 times the area of the principal surface of the piezoelectric element 101a, the panel 102a can deform in conjunction with expansion and contraction or bending of the piezoelectric element 101a, and the area of contact with the user's ear can be sufficiently guaranteed. The area of the panel is, for example, more preferably between 0.8 and 5 times the area of the piezoelectric element. Accordingly, the principal surface of the panel 102a for example has a width of 10 mm and a length of 18 mm. The principal surface of the panel 102a is described below as having a width of 10 mm and a length of 18 mm.
The vibrating body 10a illustrated in
The vibrating body 10a is preferably pressed against the user's ear with a force of 0.1 N to 3 N. If the vibrating body 10a is pressed with a force between 0.1 N and 3 N, vibration by the vibrating body 10a is sufficiently transmitted to the ear. Furthermore, if the pressure is a small force of less than 3 N, the user suffers little fatigue even when wearing the hearing aid 1 for an extended period of time, thus maintaining a sense of comfort when wearing the hearing aid 1.
As also illustrated in
Next, the acoustic characteristics of the hearing aid 1 according to one of the disclosed embodiments are described with reference to
As illustrated in
Conversely, the vibrating body 10a is contacted to the user's tragus from inside the user's ear in
As preferred examples of the user's ear position, it suffices for a peripheral portion of the ear, such as the helix, auricular tubercle, earlobe, or the like to be located between the microphone 20a and the vibrating body 10a. Alternatively, apart from a peripheral portion, the inferior antihelix crus, antihelix, or the like may be located between the microphone 20a and the vibrating body 10a.
According to the hearing aid 1, vibration of the vibrating body 10a causes the user's ear to hear sound. Sound pressure of low-frequency sound can thus be ensured by the human body vibration sound, suppressing a loss in the sense of volume. Furthermore, since it is unnecessary to provide a vent for preventing low-frequency sound from escaping, a loss in the sense of comfort when wearing the hearing aid 1 can be suppressed.
Measurement of Acoustic Device with Measurement System
Next, the results of measuring the acoustic device 1 with the above-described measurement system 10 are described. The vibrating body 10a of the acoustic device 1 is preferably pressed against the ear model 50 of the measurement system 10 with a force of 0.05 N to 3 N. This is the range over which the vibrating body 10a of the acoustic device 1 is pressed against a human ear. The vibrating body 10a is more preferably pressed against the ear model 50 with a force of 0.1 N to 2 N. This is the range over which the vibrating body 10a of the acoustic device 1 is likely to be pressed against a human ear. In other words, pressing the vibrating body 10a against the ear model 50 with a force of 0.1 N to 2 N yields measurement results more closely conforming to the actual form of use.
The area of the vibrating body 10a of the acoustic device 1 that contacts the ear model 50 of the measurement system 10 (contact area) is preferably from 0.1 cm2 to 4 cm2. This range of contact area is the range over which the vibrating body 10a of the acoustic device 1 contacts a human ear. The contact area is more preferably from 0.3 cm2 to 3 cm2. This is the range over which the vibrating body 10a of the acoustic device 1 is likely to contact a human ear. In other words, setting the contact area to be from 0.3 cm2 to 3 cm2 cm yields measurement results more closely conforming to the actual form of use.
In
Next,
Next,
It is thus clear that harmonics in the power spectrum are produced by air-conducted sound and are not produced much by the human body vibration sound.
While the results for removing the ear model 50 from the measurement system to expose the microphone 62 and measuring only the component generated by the panel 102a as air-conducted sound (conceptually, II in
Therefore, from the above-described results, it is thought that at least among the vibration component generated by the panel 102a, the component converted to air-conducted sound (III in
As comparative examples,
Next,
The number of harmonics counted under the above-described predetermined condition for counting is more preferably four or more. The number of harmonics counted under the above-described predetermined condition for counting is even more preferably five or more. The frequency band in which the harmonics are generated is preferably within the audible band.
Three or more of the above-described harmonics at or above the sixth harmonic are preferably within a range of 3 kHz to 10 kHz with respect to a fundamental frequency of 300 Hz to 1 kHz. Four or more of the above-described harmonics at or above the sixth harmonic are more preferably within a range of 3 kHz to 10 kHz with respect to a fundamental frequency of 300 Hz to 1 kHz. Five or more of the above-described harmonics at or above the sixth harmonic are more preferably within a range of 3 kHz to 10 kHz with respect to a fundamental frequency of 300 Hz to 1 kHz.
In this way, according to the disclosed acoustic device 1, harmonics at or above the sixth harmonic are generated at a high volume (level). Therefore, the disclosed acoustic device 1 allows perception of a bright, clear sound.
While an example in which the acoustic reproduction device is a hearing aid 1 has been described in this embodiment, this example is not limiting. For example, the acoustic reproduction device may be a headphone or earphone, in which case the microphone 20a is not provided. In this case, the acoustic reproduction device may reproduce sound based on music data stored in an internal memory of the acoustic reproduction device or sound based on music data stored on an external server or the like and transmitted over a network.
In this embodiment, although measurement is made while contacting the vibrating body 10a of the acoustic device 1 to the tragus of the ear model 50 in the measurement system 10, the vibrating body 10a may be contacted to any part of the ear model 50 in the measurement system 10. For example, the vibrating body 10a may be contacted to the auricle of the ear model 50 in the measurement system 10.
While the fundamental frequency generated by the acoustic device 1 in this embodiment is 500 Hz, the fundamental frequency is not limited to being 500 Hz. The fundamental frequency may be a sound at any predetermined frequency within a range of 300 Hz or greater to 1000 Hz or less, such as 400 Hz, 800 Hz, or the like.
Embodiment 2The following describes Embodiment 2. As compared to Embodiment 1, the structure of the acoustic device 1 differs in Embodiment 2. The remaining structure is the same as in Embodiment 1. An example of the acoustic device 1 being a hearing aid 1 is described, as in Embodiment 1. Where the structure is the same as in Embodiment 1, the same reference signs are applied, and a description thereof is omitted.
As illustrated in
The ear hook 62b contacts the outside of the user's auricle to mount the hearing aid 1 on the user's ear. The ear hook 62b is preferably shaped as a hook conforming to the user's auricle so as to mount the hearing aid 1 stably on the user's ear. The other end of the ear hook 62b is connected to the body 63a. The body 63a stores the microphone 20a, controller 30a, volume and sound quality adjustment interface 40a, and memory 50a therein.
The piezoelectric element 101a is joined to the panel 102a by a joining member. The joining member is disposed between the principal surface of the piezoelectric element 101a and the principal surface of the panel 102a. The joining member is preferably a non-heat hardening adhesive material or double-sided tape. Apart from the surface joined to the panel 102a, the piezoelectric element 101a is covered by a mold 103a.
The principle surface of the panel 102a includes the concavity 104b. The concavity 104b is a recessed portion in the central region of the panel 102a. Since the tragus projects outward, it is necessary to secure the area of contact by crushing the tragus when contacting a flat surface thereto. Conversely, since the hearing aid 1 includes the concavity 104b, and this concavity 104b is contacted to the tragus, the area of contact can be secured without crushing the tragus. Since it is not necessary to crush the tragus, the holder 60b can have a simple structure. Furthermore, since the tragus is not crushed, a sense of comfort can be maintained when the user wears the hearing aid 1.
The panel 102a of the vibrating body 10a is pressed against the user's ear with a force of 0.1 N to 3 N. If the panel 102a is pressed with a force between 0.1 N and 3 N, vibration by the panel 102a is sufficiently transmitted to the ear. Furthermore, if the pressure is a small force of less than 3 N, the user suffers little fatigue even when wearing the hearing aid 1 for an extended period of time, thus maintaining a sense of comfort when wearing the hearing aid 1.
The concavity 104b of the panel 102a preferably includes a portion that contacts the user's ear (for example, the tragus) and a portion that does not contact the user's ear. By providing a portion that does not contact the user's ear within the panel 102a, generation of air-conducted sound may be allowed from this portion.
The principal surface of the panel 102a preferably has an area between 0.8 and 10 times the area of the principal surface of the piezoelectric element 101a. If the principal surface of the panel 102a has an area between 0.8 and 10 times the area of the principal surface of the piezoelectric element 101a, the panel 102a can deform in conjunction with expansion and contraction or bending of the piezoelectric element 101a, and the area of contact with the user's ear can be sufficiently guaranteed. The area of the panel is, for example, more preferably between 0.8 and 5 times the area of the piezoelectric element.
Transmission of sound from the hearing aid 1 according to Embodiment 2 is similar to the outline, as illustrated in
Also when measuring the acoustic device 1 (hearing aid 1) of Embodiment 2 with the measurement system 10, three or more harmonics that are at or above the sixth harmonic and that have a volume exceeding a volume 45 dB below the volume of the fundamental frequency are measured under the above-described count condition with regard to the air-conducted sound, as with the acoustic device of Embodiment 1. Three or more harmonics at or above the sixth harmonic and exceeding a volume that is half of the volume of the fundamental frequency are also measured. With regard to human body vibration sound as well, as with the acoustic device of Embodiment 1, three or more harmonics at or above a sixth harmonic and having a measured value exceeding a value 45 dB below the measured value of the fundamental frequency are not measured. Furthermore, three or more harmonics at or above the sixth harmonic and exceeding a value that is half of the measured value of the fundamental frequency are not measured. Accordingly, for the acoustic device 1 of Embodiment 2 as well, with regard to the sound that is a combination of the air-conducted sound and human body vibration sound, three or more harmonics that are at or above the sixth harmonic and that have a volume exceeding a volume 45 dB below the volume of the fundamental frequency are measured. Three or more harmonics at or above the sixth harmonic and exceeding a volume that is half of the volume of the fundamental frequency are also measured.
Embodiment 3The following describes Embodiment 3. As compared to Embodiments 1 and 2, the structure of the measurement system 10 differs in Embodiment 3. The remaining structure is the same as in Embodiment 1 or 2. Where the structure is the same as in Embodiment 1 or 2, the same reference signs are applied, and a description thereof is omitted.
The artificial ear 131 forms an ear model and includes, like the ear model 50 in Embodiment 1, an artificial auricle 132 and an artificial external ear canal unit 134, joined to the artificial auricle 132, in which an artificial external ear canal 133 is formed, as illustrated by the side view in
A holder 150 is attached to the head model 130 detachably and includes a head fixing portion 151 for fixing to the head model 130, a support 152 that supports the acoustic device 1 targeted for measurement, and an articulated arm 153 connecting the head fixing portion 151 and the support 152. The holder 150 is configured so that, like the holder 70 in Embodiment 1, the pressing force and contact position, on the artificial ear 131, of the acoustic device 1 supported by the support 152 can be adjusted via the articulated arm 153.
The measurement system 110 of this embodiment yields measurement results similar to those of the measurement system 10 of Embodiment 1. Among other effects, in this embodiment, the acoustic device 1 is evaluated by detachably mounting the artificial ear 131 for vibration detection on the human head model 130, thus allowing evaluation that conforms more closely to the actual form of use by taking into consideration the effect of the head.
Although this disclosure is based on embodiments and drawings, it is to be noted that various changes and modifications will be apparent to those skilled in the art based on this disclosure. Therefore, such changes and modifications are to be understood as included within the scope of this disclosure. For example, the functions and the like included in the various units and members may be reordered in any logically consistent way. Furthermore, units and members may be combined into one or divided.
REFERENCE SIGNS LIST
-
- 1 Acoustic device (hearing aid)
- 10, 110 Measurement system
- 20 Acoustic device mount
- 30 Base
- 31 A/D converter
- 32 Signal processor
- 33 D/A converter
- 34 Piezoelectric amplifier
- 50 Ear model
- 51 Artificial auricle
- 52 Artificial external ear canal unit
- 53 Artificial external ear canal
- 54 Support member
- 55 Vibration gauge
- 56 Vibration detection element
- 60 Sound pressure gauge
- 61 Tube member
- 62 Microphone
- 70 Holder
- 71 Support
- 72 Arm
- 73 Movement adjuster
- 10a Vibrating body
- 11a Pressing member
- 12a Attaching portion
- 20a Microphone
- 30a Controller
- 40a Volume and sound quality adjustment interface
- 50a Memory
- 60a, 60b Holder
- 61a, 61b Support
- 62a, 62b Ear hook
- 63a Body
- 101a Piezoelectric element
- 102a Panel
- 103a Mold
- 104b Concavity
- 105b Convexity
- 111a Cutout portion
- 120 Acoustic device mount
- 130 Head model
- 131 Artificial ear
- 132 Artificial auricle
- 132 Artificial auricle
- 133 Artificial external ear canal
- 134 Artificial external ear canal unit
- 135 Vibration detector
- 136 Sound pressure gauge
- 150 Holder
- 151 Head fixing portion
- 152 Support
- 153 Articulated arm
- 200 Measurement unit
- 300 Sensitivity adjuster
- 301, 302 Variable gain amplifier circuit
- 400 Signal processor
- 410 A/D converter
- 411, 412 A/D conversion circuit
- 420 Frequency characteristic adjuster
- 421 Equalizer
- 430 Phase adjuster
- 431 Variable delay circuit
- 440 Output combiner
- 450 Frequency analyzer
- 460 Memory
- 470 Signal processing controller
- 500 PC
- 510 Connection cable
- 520 Display
- 521 Application screen
- 522-524 Icon
- 525 Measurement result display area
- 526 Icon to change measurement range
- 527 Measurement result display selection area
- 528 File icon
- 529 Measurement type icon
- 530 Help icon
- 600 Printer
- 601, 602 Arrow
Claims
1. An acoustic device for transmitting sound to a user through vibration conduction by contacting a vibrating body to a human auricle, wherein
- when a measurement system, provided with an ear model including an artificial auricle and an artificial external ear canal and with a microphone that measures air-conducted sound in the artificial external ear canal, measures the air-conducted sound upon the acoustic device outputting a fundamental frequency at a predetermined frequency in an audible frequency band while placed in contact with the ear model,
- three or more harmonics at or above a sixth harmonic and having a volume exceeding a volume 45 dB below a volume of the fundamental frequency are measured under a first predetermined count condition.
2. The acoustic device of claim 1, wherein the vibrating body is pressed against the ear model with a force of 0.05 N to 3 N.
3. The acoustic device of claim 1, wherein the vibrating body is pressed against the ear model with a force of 0.1 N to 2 N.
4. The acoustic device of claim 1, wherein the vibrating body includes a piezoelectric element and a panel that flexes by being bent directly by the piezoelectric element.
5. The acoustic device of claim 1, wherein a contact surface of the vibrating body with respect to the ear model is from 0.1 cm2 to 4 cm2.
6. The acoustic device of claim 1, wherein a contact surface of the vibrating body with respect to the ear model is from 0.3 cm2 to 3 cm2.
7. The acoustic device of claim 1, wherein
- a vibration gauge that measures vibration in the ear model is further provided, and
- when measuring the vibration upon the acoustic device outputting the fundamental frequency while placed in contact with the ear model,
- three or more harmonics at or above a sixth harmonic and having a measured value exceeding a value 45 dB below a measured value of the fundamental frequency are not measured.
8. The acoustic device of claim 1, wherein the fundamental frequency is a predetermined frequency of 300 Hz or greater to 1000 Hz or less.
9. The acoustic device of claim 1, wherein the first predetermined condition is that harmonics having a signal-to-noise ratio (S/N) of 10 dB or more above a noise floor are counted.
10. The acoustic device of claim 1, wherein a frequency band in which the harmonics are measured is an audible band from 50 Hz to 20 kHz.
11. The acoustic device of claim 1, wherein a frequency band in which the harmonics are measured is an audible band from 3 kHz to 10 kHz.
12. A method of using an acoustic device, comprising placing the acoustic device of claim 1 against a user's auricle and hearing sound.
13. A method of using an acoustic device, comprising placing the acoustic device of claim 1 against a tragus of a user's auricle and hearing sound.
14. An acoustic device for transmitting sound to a user through vibration conduction by contacting a vibrating body to a human auricle, wherein
- when a measurement system, provided with an ear model including an artificial auricle and an artificial external ear canal and with a microphone that measures air-conducted sound in the artificial external ear canal, measures the air-conducted sound upon the acoustic device outputting a fundamental frequency at a predetermined frequency in an audible frequency band while placed in contact with the ear model,
- three or more harmonics at or above a sixth harmonic and exceeding a volume that is half of a volume of the fundamental frequency are measured under a second predetermined count condition.
15. The acoustic device of claim 14, wherein
- a vibration gauge that measures vibration in the ear model is further provided, and
- when measuring the vibration upon the acoustic device outputting the fundamental frequency while placed in contact with the ear model,
- three or more harmonics at or above a sixth harmonic and exceeding a value that is half of a measured value of the fundamental frequency are not measured under a predetermined count condition.
16. The acoustic device of claim 14, wherein the second predetermined condition is that the volume of the fundamental frequency is 70 dB or greater.
17. An acoustic device for transmitting sound to a user through vibration conduction by contacting a vibrating body to a human auricle, wherein
- when a measurement system, provided with an ear model including an artificial auricle and an artificial external ear canal, a microphone that measures air-conducted sound in the artificial external ear canal, and a vibration gauge that measures vibration in the ear model, measures volume that is combined based on a value measured by the microphone and a value measured by the vibration gauge upon the acoustic device outputting a fundamental frequency at a predetermined frequency in an audible frequency band while placed in contact with the ear model,
- three or more harmonics at or above a sixth harmonic and having a volume exceeding a volume 45 dB below a volume of the fundamental frequency are measured under a first predetermined count condition.
18. The acoustic device of claim 17, wherein
- when measuring the vibration upon the acoustic device outputting the fundamental frequency while placed in contact with the ear model,
- three or more harmonics at or above a sixth harmonic and having a measured value exceeding a value 45 dB below a measured value of the fundamental frequency are not measured under a predetermined count condition.
19. An acoustic device for transmitting sound to a user through vibration conduction by contacting a vibrating body to a human auricle, wherein
- when a measurement system, provided with an ear model including an artificial auricle and an artificial external ear canal, a microphone that measures air-conducted sound in the artificial external ear canal, and a vibration gauge that measures vibration in the ear model, measures volume that is combined based on a value measured by the microphone and a value measured by the vibration gauge while the acoustic device is placed in contact with the ear model,
- three or more harmonics at or above a sixth harmonic and exceeding a volume that is half of a volume of a fundamental frequency are measured under a third predetermined count condition.
20. The acoustic device of claim 19, wherein
- when measuring the vibration upon the acoustic device outputting the fundamental frequency while placed in contact with the ear model,
- three or more harmonics at or above a sixth harmonic and exceeding a value that is half of a measured value of the fundamental frequency are not measured under a predetermined count condition.
21. The acoustic device of claim 19, wherein the third predetermined condition is that the volume of the fundamental frequency is 75 dB or greater.
20140283614 | September 25, 2014 | Inagaki et al. |
2002-315098 | October 2002 | JP |
2005-311415 | November 2005 | JP |
2005-348193 | December 2005 | JP |
2007-019898 | January 2007 | JP |
2007-103989 | April 2007 | JP |
2007-221532 | August 2007 | JP |
2009-036995 | February 2009 | JP |
2013-078116 | April 2013 | JP |
2013/172039 | November 2013 | WO |
- International Search Report issued in PCT/JP2014/064042, mailed Jun. 24, 2014.
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Type: Grant
Filed: May 21, 2014
Date of Patent: Oct 31, 2017
Patent Publication Number: 20160134977
Assignee: KYOCERA Corporation (Kyoto)
Inventor: Tomohiro Inagaki (Yokohama)
Primary Examiner: Paul S Kim
Assistant Examiner: Sabrina Diaz
Application Number: 14/893,556
International Classification: H04R 29/00 (20060101); H04R 25/00 (20060101); H04R 17/00 (20060101);